The 29-year-old, who is his country's record goalscorer, has been struggling with tendinosis in his left knee, as well as a thigh injury, which caused him to miss his Portugal's warm-up fixtures against Greece and Mexico.

With the Real Madrid forward not having trained with his team-mates since joining up with the squad last week, there had been concerns that he would miss his country's opening Group G game against Germany.

However, the Portuguese Football Association provided an encouraging update on both Ronaldo and midfielder Raul Meireles, who had also been struggling with injury.

An FPF statement read: "Cristiano Ronaldo and Raul Meireles integrated with the remaining group of players."

Former Liverpool player Meireles, who now plays for Fenerbahce in Turkey, had been struggling with a muscular problem.

In addition, central defender Pepe worked away from the main group of players as he continued his own recovery from a leg injury.

The statement added: "Pepe is carrying out his rehabilitation and sport specific exercises in the field individually."

Portugal's opening fixture with the Germans is on Monday 16 June, with their subsequent Group G fixtures against the USA and Ghana on Sunday 22 June and Thursday 26 June respectively.